Load break disconnect



' INVENTOR Herb erll. H aw I ins 2 Sheets-Sheet l H. L. RAWLINS LOADBREAK DISCONNECT ,Filed Feb. 20.

Jan. 12, 1943.

WITNESSES:

ATTO Patented Jan. 12, 1943 LOAD BREAK DISCONNECT Herbert L Rawlins,Wilkinsburg, Pa., assignor a.

Westinghouse Electric & Manufacturing Company, East Pittsburgh, Pa., acorporation of Pennsylvania Application February 20, 1940, Serial No.319,897

6 Claims. (Cl. 200-62) My invention relates generally to electriccircuit interrupting devices, and more particularly to disconnectingswitches which are capable of interrupting load currents.

Disconnecting switches of the ype where a conducting blade member ismounted for movement into and out of engagement with respect to one 1separated from a cooperating contact.

Another object of my invention is to provide a disconnecting switchhaving a mainblade, with novel auxiliary interrupting blade meansoperable to quickly interrupt the circuit after the main disconnectingswitch blade has moved to an open position.

A further object of my invention is to provide a disconnecting switch ofthe type described having quick acting auxiliary blade means, with novelare extinguishing means for the auxiliary blade.

A further object of my invention is to provide as an attachment for astandard type of disconnecting switch blade, a novel auxiliary bladeunit of the quick-break type.

Another object of my invention is to provide a novel arc chute structureadapted to cooperate with separable contacts of a circuit interrupter tosuppress and extinguish the arc formed upon separation of such contacts.

Another object of my invention is to provide a novel are chute structurewhich is designed as an attachment for a standard type of disconnectingswitch structure.

These and other objects of my invention will become more apparent uponconsideration of the following specification of a preferred embodimentthereof, taken in connection with the attached drawings, in which:

Figure 1 is a side elevatlonal view of a disconnecting switch embodyingmy invention;

Fig. 2 is a view similar to'Fig. 1 showing the disconnecting switch in apartially open position, and having a portion' of one wall of the arcchute broken away to illustrate the interior construction thereof; I

Fig. 3 is a partial transverse, cross-sectional view through the arcchute substantially on the line III-J11 of Fig. 1 and illustrating themain disconnecting switch in elevation;

Fig. 4 is a transverse, cross-sectional view taken through the arc chutesubstantially on the line IVIV of Fig. l and showing the maindisconnecting switch blade and contact in elevation;

Fig. 5 is a cross-sectional view of the auxiliary blade supporting meanstaken substantially on the line VV of Fig.3 and showing a portion of themain switch blade; and

Fig. 6 is a view similar to Fig. 5 with the parts in a positioncorresponding to that shown in Fig. 2.

Referring to the drawings and particularly to Figs. 1 and 2 thereof, Ihave shown portions of spaced supporting insulators 2 and 4,respectively, for supporting a disconnecting switch embodying the novelfeatures of my invention. As shown, the supporting insulator 2 hassecured to the end cap 6 thereof as by the machine screws 9, a contactbase member 1 having an integral depending terminal portion 8 for theconnection of a line conductor thereto. The contact support I may be ofany suitable conducting material such, for example, as copper or thelike, and further includes an outstanding integral hinge tongue H) forpivotally supporting the disconnecting switch blade [2. As appears moreclearly from Figs. 3 and 4, the switch blade I2 is of a splitconstruction, and includes the spaced blade sides I4. The blade sides Iare pivotally mounted on the hinge tongue III with the sides located onopposite sides of the hinge tongue, respectively, by a hinge bolt I6passing through the blade sides and hinge tongue, with resilient,cup-shaped spring washers l8 disposed between the head of the boltandits nut, and the outer sides of the blade sides H. The hinge mountingfor the blade thus far described is of a conventional type and mayinclude limited area contact portions forming the contact between theblade sides 14 and the hinge tongue III in substantially the same mannerdisclosed in the copending application of H. J. Crabbs, Serial No.268,906, filed April 20, 1939, and assigned to the same assignee of thisapplication.

The insulator I, at the break end of the disconnecting switch blade isalso provided with end cap 20, on which is seated an auxiliary bladecontact supportingbase member 22, which in turn is clamped or secured tothe insulator 4 together with the break contact base member 24, by thebolts 28 passing through these members to find threaded engagement inthe insulator cap 2!. The break contact base member 24 is provided withan integral upstanding break tongue 28, which is slotted at its outerend as shown at 30 (Fig. 3) to receive a bolt 32 connecting the breakends of the blade sides M. The bolt 32 extends through the blade sidesl4, and resilient cupshaped washers 34 at the outer sides thereof, tomaintain the blade sides together. A spacing sleeve 33 is provided onthe bolt 32 between the blade sides l4 for preventing undue movement ofthe blade sides towards each other. An operating handle 36 is securedbetween the outer ends of the blade sides l4 in any desired manner,such,

' for example, as by rivets or the like, and includes an aperture 31,for the reception of a hookstick operating member or the like. The breakend of the blade may also be provided with raised limited area contactportions 38 for engaging the break tongue, and such contact portions maybe of the type disclosed in the above-mentioned copending application.

The structure thus far described is in many respects conventionaldisconnecting switch structure, which may be operated to interrupt thecircuit merely by pivoting the switch blade l2 in a counter-clockwisedirection about its pivot l6, as viewed in Figs. 1 and 2. Such switchstructures, however, are generally incapable of safely interrupting loadcurrents, inasmuch as they depend entirely upon attenuation of the areformed when the switch blade is opened, to increase the arc voltage andextinguish the arc. Obviously, especially in high voltage applications,the arc may not be extinguished until the switch blade has been opened asubstantial distance and the arc formed being exposed, may jump toadjacent apparatus or even to the operator. Therefore, I haveincorporated as a part of .a conventional disconnecting switchstructure, to render such switches capable of interrupting load currentseven at high voltages, and to extinguish any arcs formed upon openingthe switch in a relatively minor portion of the opening movement of theswitch, with such arcs entirely confined, to thereby eliminate alldanger in the operation of the switch, and provide a' switch which iscapable of interrupting load currents in a relatively simple, yetefiicient, manner. The interrupting structure which I have devisedfurthermore is capable of attachment to conventional types ofdisconnecting switches in a relatively simple man gswitch blade l2, andextends outwardly through the open space in the. U-form side wall of theblock 42, with the head thereof positioned at a point spaced inwardly ofthe opposite wall 46 of the block 42. A spacer sleeve 56 is provided onthe bolt 54 between the head thereof and the adjacent blade side M toposition the head of this bolt, as shown in Fig. 3. A second spacingsleeve 58 is provided on the bolt 54 between the blade I sides l4, tomaintain the same in spaced relation. The bolt 54 is provided with a nut60 to secure the same in position.

As stated above, the wall 48 of the auxiliary blade supporting block 42is substantially U- shaped in form, as shown in Figs. 5 and 6, toprovide a pair of spaced substantially radially extending stopshoulders62 and 64, respectively, with the stop bolt 54 having the end thereofreceived in the space between the stop shoulders 62 ner and withoutinvolving any extensive modifl- V cation of such existing switches.v

I provide an auxiliary switch blade 40 which, as appears from Figs. 1and 2 of the drawings, has its outer end tapered, with the inner endthereof substantially rectangular in form and secured to a supportingblock 42 which is in turn pivotally mounted on the main disconnectingswitch blade l2. The auxiliary blade 40 is secured to the supportingblock 42 as, for example, by the machine screws 44. The supporting block42 is in the form of a casting, or the like, having one side wall 46 towhich the auxiliary blade 46 is secured, and an opposite side 48 whichis generally U- shaped in form, and which is seated upon the outer sideof the blade side l4. The main disconnecting switch blade I2 is modifiedsolely by the provision of a pair of laterally spaced aperturesextending through both blade sides l4, for mounting the auxiliary blade40 thereon. A pivot bolt 50 extends through the auxiliary blade 40, theauxiliary. blade supporting block 42,-and

through one of the apertures through the main blade l2 to pivotallysupport the block 42. The pivot bolt 50 is provided with a spacer sleeve52 and 64. A coil spring 66 is provided about the spacing sleeve 52 andhas one end thereof engaged with an inner extension of one screw 44,

as is clearly shown in Figs. 3, 5 and 6., The otherend thereof isextended to engage the stop bolt spacer sleeve 56, which is fixed to themain disconnecting switch blade l2 by bolt 54. As is apparent from Figs.5 and 6, the coil spring 66 tends to maintain the supporting block 42,and consequently the auxiliary switch blade 40, in the position in whichit is substantially parallel to the main disconnecting switch blade I2and wherein the stop shoulder 64 of the switch block 42 is maintained inengagement with the stop bolt 54. This is the normal position of theauxiliary switch blade 40 with respect to the main switch blade l2 andis illustrated in Figs. 1, 3, 4 and 5.

Referring to Fig. 4, it will be observed that the supporting base member22 is provided with an integral substantially perpendicularly disposedprojecting flange portion 12 for supporting a contact cooperative withthe auxiliary blade, and an arc chute structure. Contact strips I4 aredisposed at opposite sides of the flange l2, backed by resilient leafcontact springs 16, with insulating plates 18 enclosing the contactstructure, and

all beingsecured to the flange 12 by the bolts 80, extending through thecontact strips 14, spring members 16, insulating plates 18, and thesupporting member 12., The supporting flange 12- a slot forthe'reception of the outer end of the auxiliary switch blade 40therebetween. The contact strips 14 are clamped in position, as shown inFig. 4 so that the outer ends thereof converge slightly, and the innersides of the outer edges are turned inwardly and then outwardly, to forminwardly convex, opposed surfaces on the outer edges of the contactstrips 74. The contact strips 14, supporting flange l2 and base 22 maybe of any desired conducting material such, for example, as copper orthe like. The contact strips 14 are resiliently backed and maintainedagainst separation by the leaf spring members 16 intimately engaged withthe outer sides of these contact strips. The leaf spring members 16 maybe of any desired resilient material such, for example, asphosphor-bronze or the like. The insulating plates 18 may be of anydesired insulating material such, for example, as a moulded insulatingmaterial, fiber, or. the like and have the outer edges thereofbeveled,,as shown in Fig. 4 to provide a converging entrance to the slotbetween these plates. The plates 18 are preferably provided with linerplates 83 which have cut-out portions or slots 82, as shown in Fig. 2for receiving the contactstrips l4 and their resilient backing members16. The liner plates 83 are preferably of a material which is capable ofevolving an arc extinguishing gas when in proximity to an electric aresuch, for example,

' as fiber, boric acid, or a synthetic resin. The

liner plates are secured in position with respect to the insulatingplates 18 as by the screws 8| If desired, the insulating plates 18 maybe of a gas evolving material similar to plates 80, in which event theliner plates may be dispensed with.

Whether or not the insulating plates 18 are provided with liner plates83, the slot provided between the plates for the reception of theauxiliary blade 40 should be substantially equal to the thickness of theblade, and in any event, should be less than twice the blade thicknessto obtain effective arc extinguishing properties. The auxiliary bladeIll itself is preferably very thin so that the slot formed between theinsulating members 18 may likewise be thin. Thus, for example, in oneform of switch constructed in accordance with this invention and whichwas built and successfully tested, the slot was about /8" wide and theswitch successfully interrupted currents of 400 amperes at 2300 volts,and 200 amperes at 4600 volts.

As shown in Figs. 1, 3, 4 and 5, the switch is in its normal closedposition with the main switch blade 12 in engagement with its breakcontact tongue 28, and with the auxiliary switch blade 80 receivedbetween the contact strips H in the arc chute. When it is desired tointerrupt the circuit, the operating member 31 on the main switch bladeI2 is moved in a direction to move the main blade l2 in acounter-clockwise direction from that shown in Fig, 1 to that shown inFig. 2. This will separate the main switch blade 12 from contact tongue28 and cause slight movement of the outer end of the auxiliary blade 30from the position shown in Fig. 1 to a position where it engages theinwardly turned outer ends of the contact strips H, as shown in Fig. 2.The outer end of the auxiliary blade is'retained in this po. sition fora substantial amount of the opening movement ofthe main switch blade bythe inwardly turned ends of the contact strips 14, so that even throughthe main switch blade is in an open position the circuit is stillunbroken through the switch, since it is shunted through the auxiliaryblade 48 and contact strips 14. In the movement of the main switch bladefrom the position shown in Fig. 1 to the position shown in Fig. 2, theauxiliary blade 48 will move relatively clockwise about its pivot. withrespect to the main switch blade l2. This relative movement between themain switch blade and the auxiliary switch blade 48 will act to stressthe coil spring 66 mounted in the block 42, and these parts will assumethe position shown in Fig. 6. When the parts arrive at the positionshown in Figs. 2 and 6, the shoulder 62 on the supporting block 42 comesinto engagement with the stop bolt 84 which is fixed relative to themain switch blade l2. Relative movement between the two blades isthereby prevented upon continued movement of the main switching blade l2in the opening direction, and upon such continuation of movement, theauxiliary blade All is pulled clear of the inwardly turned outer ends ofthe contact strips 14, thereby permitting the coil spring 66 to quicklymove the auxiliary blade 40 with a snap action out through the slot inthe arc chute to a position in which it is again substantially inparallel relation with respect to the main switch blade i2. Thismovement of the auxiliary blade 48 through the arc chute will extinguishthe are formed in a manner to be hereinafter referred to while confiningit within the arc chute. The switch may thereafter with safety, be movedto a full open position. To close the switch, the main blade I2 is movedin a clockwise direction from its open position and both the main bladel2 and the auxiliary blade 40 are brought into engagement with theirrespective contacts 28 and H, substantially simultaneously to close thecircuit. In the closing operation the blades are constrained to movetogether since engagement of shoulder 64 of block 42 with stop bolt 54,prevents relative counter-clockwise movement of the auxiliary blade. Inthe closing operation, when the auxiliary blade 40 engages the outerends of contact strips 14, it is enabled to supply force to provide anentrance therebetween by its engagement with the outer inwardly convexportions of the contact strips 14. Separation of the contact strips 14is permitted by yielding of the resilient backing strips 16 inengagement therewith. As appears in Fig. 4, normally the free.end of theauxiliary switch blade 40 lies below the outer inturned ends of thecontact strips H, and may be entirely out of engagement with respect tothe strips. The only time that it is necessary for the auxiliary blade40 to engage the contact strips 14 is during the opening movement of theswitch to shunt the circuit therethrough, as heretofore described.

As stated heretofore, the slot provided between the insulating members18 and may be extremely narrow due to the use of a very thin auxiliaryblade 40, and this allows the provision of a small clearance between theblade and the insulating members 18 and 83. Therefore, when theauxiliary blade is snapped open, the arc is not only attenuated toincrease its arc voltage as in conventional switch structures, but isalso conlined in a narrow slot which additionally acts to increase thearc voltage, and furthermore, when a lining 83 of gas evolving materialis used, the arc flowing between the spaced walls of such material issubjected to such evolved un-ionized gases to thereby extinguish the areat a current zero and prevent restriking of the same. With the structurewhich I have disclosed, therefore, it -is apparent that there are threefactors which contribute to extinguishing the are formed upon openingthe switch, namely: (1) lengthening of the arc, (2) confining the arc ina narrow space, and (3) subjecting the arc to a blast of un-ionized gas.It is apparent that the supporting fiange member 12 acts to close thebottom of the slot between arc chute plates 18 and 83, as viewed in Fig.4, and the outer adjacent side of the slot is closed by an insulatingspacer member 19, as

shown in Fig. 3, whereby the gas evolved from the lining material '83 isforced to pass out of the slot in the arc chute at the two remainingsides of the slot. This will act to increase the effect of the gas blastproduced by the gases evolved by the lining 83 when subjected to anelectric arc. It should be noted that the depth of the slot is manytimes thewidth of the portion of the auxiliary blade 40 receivedtherein, and is proportioned substantially so that when the auxiliaryblade fsnaps open, the main switch blade I2 is still in a positionsubstantially in the plane of the arc chute so that the auxiliary blade4!! acts to interrupt the circuit substantially entirely within the arcchute slot so as to confine the are formed to the chute. In other words,the break distance of the auxiliary blade is substantially entirelyconfined to the slot in the arc chute.

From the foregoing it should be apparent that I have provided a noveldisconnecting switch structure capable of interrupting load currentswith safety and with less travel of the discon necting switch blade thanhas heretofore been possible. Also, I have provided a quick openingauinliary blade structure especially constructedand adapted for readyattachment to conventional switch blade structures at one side of suchblades, it being necessary merely to provide two apertures through theblade to attach my novel auxiliary blade structure thereto. I have alsoprovided a novel are extinguishing structure for use with the auxiliaryblade structure described above, and which also can be readily attachedto a disconnecting switch contact structure.

As stated heretofore, the entire arc chute structure, together with thebreak contact for the auxiliary blade, is supported by a single supportmember 22 which can be secured to the maiii disconnecting switch breakcontact and its insulator support, utilizing the bolts which normallysupport the main break contact on the insulator. Also, it should benoted that in the closed position of my novel switch structure, theauxiliary blade contacts are contained within an arc chute structuretogether with the outer end of the auxiliary blade, and the are formedis substantially entirely confined within this structure and is entirelyextinguished upon relatively slight movement of the auxiliary switchblade away from its opposed contacts 14.

Although I have shown my novel interrupting structure as applied to aconventional disconnecting switch wherein this structure has certainparticular novel features of cooperation, it should be obvious that theauxiliary blade structure, together with the arc chute structuretherefor, is also capable of use with other types of blades, findingparticular utility, for example, in an enclosed type of disconnectingswitch wherein the opening movement is determined by the size of theswitch enclosure. Therefore, it is obvious that an enclosed switchconstructed in accordance with my invention will be capable ofinterrupting load currents in a smaller enclosure than the conventionaltype of disconnecting switch because of the relatively small travel ofthe blade structurenecessary to open the circuit and extinguish the arcformed. Similarly, my invention may also be applied to other types ofcircuit interrupters where it is desired to utilize a disconnectingfunction by providing an air gap in the circuit, such, for example, asin a disconnecting type of fuse.

Having described a preferred embodiment of my invention in accordancewith the patent statutes, I desire that it be understood that myinvention is not to be limited to the particular embodiment disclosed,inasmuch as it will be obvious, particularly to persons skilled in the'art,

that many changes and modifications may be made in the embodimentdisclosed without departing from the broad spirit and scope of theinvention. Therefore, I desire that my invention be interpreted asbroadly as possible, and be limited only by what is expressly set forthin the following claims.

I claim as my invention: I

1. As a new article of manufacture, an attachment for switch bladesincluding an elongated auxiliary blade member having secured adjacentone end, thereof a mounting and spacing block projecting from one sideof said member, a pivot aperture through said blade and block assemblyfor the pivotal mounting of said attachment, and spaced laterallyextending shoulders on said block adapted to providestop means forlimiting piv-' otal movement of said blade member.

2. As a new article of manufacture, an attachment for switch bladesincluding an elongated auxiliary blade member having secured adjacentone end thereof a mounting and spacing block projecting from one side ofsaid member, a pivot aperture through said blade and block assembly forthe pivotal mounting of said attachment, and opposed shoulders on theside of said block opposite said blade member spaced from the axis ofsaid pivot aperture and relatively angularly displaced about said axisto provide stop means for limiting pivotal movement of said blademember.

3. In a switch, contact means, main blade means mounted for movementinto and out of engagement with said contact means, auxiliaryquick-break blade means comprising an elongated auxiliary blade memberhaving secured adjacent one end thereof a mounting and spacing blockprojecting from one side of said member, a pivot aperture through saidblade and block assembly for the pivotal mounting of said auxiliaryblade means, opposed shoulders on vthe side of said block opposite saidauxiliary blade means spaced from the axis of said pivot aperture andrelatively angularly displaced about said axis, a pivot pin passingthrough said pivot aperture and an aperture in said main blade means topivotally meat s at a position relativeto said main blade means suchthat it is positively moved with said main blade means into engagementwith said contact means, and said resilient means causes movement ofsaid auxiliary blade means with said main blade means in a direction outof engagement with said contact means.

4. An attachment for the break contact of disconnecting switchescomprising an arc chute unit, said unit including spaced, substantiallyparallel walls of insulating material defining a narrow slottherebetween, supporting means of conducting material secured betweensaid walls adjacent one edge thereof, contact means in said slot securedto said supporting means, said supporting means extending outwardly ofsaid walls and having a laterally extending supporting portion of suchsize and shape as to'be secured between the break contact and itssupporting insulator of a disconnecting switch, so as to support contactwith said contact means electrically connected therewith and arranged sothat said'slot is located so as to receive an auxiliary snap-actingblade operatively associated with the blade of said switch.

5. An attachment for the break contact of disconnecting switchescomprising an arc chute unit, said unit including spaced, substantiallyparallel walls of insulating material defining a narrow slottherebetween, supporting means of conducting material secured betweensaid walls adjacent one edge thereof, contact means in said slot securedto said supporting means, said supporting means extending outwardly ofsaid walls and having a laterally extending flat supporting portionadapted to be secured between the break contact and its supportinginsulator or a disconnecting switch, so as to support said unit from thesame insulator supporting said break contact in a position adjacent saidbreak contact with said contact means electrically connected therewithand arranged so'that said slot is located so as to receive an auxiliarysnap-acting blade operatively associated with the blade of said switch.

' as to be secured between the break contact and 6. An attachment forthe break contact of disconnecting switches comprising an arc chuteunit, said unit including spaced, substantially parallel walls oiinsulating material'deilning a narrow slot therebetween, means includingsupporting means of conducting material secured between said wallsadjacent one edge thereof for maintaining said walls in predeterminedspaced relation and closing said one edge of said slot, contact means insaid slot secured to said supporting means, said supporting meansextending outwardly of said walls and having a laterally extendingsupporting portion of such size and shape HERBERT L. RAWLINS.

